将LibSVM输出转换为浮点数 [英] Convert LibSVM output to vector of floats
问题描述
我需要形成 HOGDescriptor :: setSVMDetector（）输入。
我用openCV计算描述符，然后使用libSVM获取模型文件。
要形成输入，我知道我需要得到支持向量的值和元素mul他们与alphas（然后添加-rho在结尾），但我不能得到这些alphas 。
我有一个SV列表，例如：
1 1：-0.0434783 2：0.153846 3：0.194444 4：-0.353712 5：-0.45054
1 1：-0.2173916 2：-0.38461 3：0.222262 4：-0.676686 5：-0.78062
解决方案 c $ c>
< 好吧，现在似乎事情很清楚。
Alphas是我的第一列。
因为我在我的测试模型中都有-1或1（dunno为什么），我认为这些都是标签。
我的解析器（但你需要在文件中只留下SV）：
std :: ifstream ifs（cars_model.model） ;
const int nsv = 90;
const int nfeatures = 144;
float rho = 12.5459;
char ts [4000] =; //！
std :: vector< float> res（nfeatures，0）;
std :: vector< float>阿尔法
Mat_< float> temp（nsv，nfeatures）;
int c = 0;
std :: cout<< 加载模型文件... \\\
;
for（int i = 0; i
float al = 0;
ifs>> al;
alphas.push_back（al）;
for（int j = 0; j< nfeatures; j ++）{
float ind，s;
char junk;
ifs>> ind>> junk>> s;
temp.at< float>（c，j）= s;
// std :: cout<< f<< ''<< s<< '\\\
';
}
c ++;
}
ifs.close（）;
std :: cout<< 计算原始形式... \\\
;
for（int i = 0; i
float alpha = alphas [i];
for（int j = 0; j
}
}
//res.push_back(-rho）;
std :: ofstream ofs（primal.txt）;
for（int i = 0; i< res.size（）; i ++）
ofs< res [i]<< '';
ofs.close（）;
你知道，它工作。您可以将rho设置为检测器的阈值。
I need to form HOGDescriptor::setSVMDetector() input.
I compute descriptors with openCV then use libSVM to get model file.
To form input i know that i need to get support vectors' values and elementwise mul them with alphas (then add -rho at the end), but i don't get where to get these alphas.
I have a list of SVs like:
1 1:-0.0434783 2:0.153846 3:0.194444 4:-0.353712 5:-0.45054
1 1:-0.2173916 2:-0.38461 3:0.222262 4:-0.676686 5:-0.78062
but where to get alphas?
解决方案 Ok, it seems things are clear now.
Alphas are the first column in my case.
Since i had all of them equal to -1 or 1 (dunno why) in my test model, i thought these were labels.
Anyway, here is my parser (but you need to leave only SVs in file):
std::ifstream ifs("cars_model.model");
const int nsv = 90;
const int nfeatures = 144;
float rho = 12.5459;
char ts[4000] = ""; // !
std::vector<float> res(nfeatures,0);
std::vector<float> alphas;
Mat_<float> temp(nsv, nfeatures);
int c = 0;
std::cout << "Loading model file...\n";
for (int i=0; i<nsv; i++) {
float al = 0;
ifs >> al;
alphas.push_back(al);
for (int j=0; j<nfeatures; j++) {
float ind, s;
char junk;
ifs >> ind >> junk >> s;
temp.at<float>(c, j) = s;
//std::cout << f << ' ' << s << '\n';
}
c++;
}
ifs.close();
std::cout << "Computing primal form...\n";
for (int i=0; i<nsv; i++) {
float alpha = alphas[i];
for (int j=0; j<nfeatures; j++) {
res[j] += (temp.at<float>(i,j) * alpha);
}
}
//res.push_back(-rho);
std::ofstream ofs("primal.txt");
for (int i=0; i<res.size(); i++)
ofs << res[i] << ' ';
ofs.close();
And you know, it works. You can set rho as threshold of the detector.
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